popping when i turn transistor amp off

[black_labb]

hi guys
i have a fender frontman 212r thats about 2-3 years old. just recently i have noticed it has been making loud popping noises when it is turned off. it varies in volume, i thought it was varying with the volume i had it on but i just got a few loud ones and a softer one on zero volume, so it seems to be varying randomly. it does it when i turn it on then off right away, aswell as when i have been playing for a while.

it doesnt do it when the lead is not plugged in, but i believe not having the lead in stopps it from making any noise whatsoever, as you dont get any hum or anything even on full (you do when a lead is plugged in, even with no guitar.


is this something i should worry about? is it becase it isnt grounded properly, or the output transformer is on its way to its death?

anyone have any tips?

should i be worried or should i just keep playing and keep track of any changes for the worse?

i have been considering making myself an amp but i wouldnt want to make one without being able to have one to play in the meantime, and i need to finish making a guitar or 2 which i have in the works.

thanks for any help

[Enzo]

Try turning the reverb down to zero before switching off. The reverb circuits tend to be sensitive to noise.

Popping at turn on/off is very common, and nothing to worry about unless it is some incredible screech or something.

The pop that comes from a solid state amp will never be any louder than the amp when it is fully cranked. SO if it can handle playing turned all the way up, it won't sweat the pop.

[black_labb]

thanks, i wouldnt be worried about it other than the fact that it has just started.

its 100w so i really hope it doesnt get anywhere near the full volume of the amp, i play it at the bare minimum. i havent played it past 3 unless i turned the guitar down (trying to put a mic and a guitar through the one amp)

i think i may just pull out the lead when turning it off if it gets annoying, right now its more of a concern.

[Enzo]

What if you turn the volume on the guitar down to zero?

[Mars Amp Repair]

yeah,
It's typically from the plus & minus voltage supplies decaying at different rates when you turn it off. It causes the opamps to output offset voltage...

since most music amps don't mute the speakers or the output stages at power down or initally at power up, there's not much you can do about it.

It usually gets worse as the filter caps age differently, however at some point I have tried to rememdy by replacing caps & almost always you can only improve it slightly. g

[Enzo]

ACtually, another reason we get pops is the power switch. As it opens, the contacts inside spark, and the amplifier amplifies that spark signal before the power supplies have a chance to discharge. Ever notice in some houses if you flip on the bedroom - or whatever - light switch, there will be a little pop in the sound of the TV? The TV is picking up the spark from that switch.

If your amp has started poppong more than before, it might be because the power switch contacts are eroding and sparking more than they used to.

Clip a big .1 @ 600v film cap across the switch terminals and see if that has an effect.

[black_labb]

What if you turn the volume on the guitar down to zero?

it does it the same,even if the guitar isnt even plugged in.


thanks guys, i just wanted to make sure that i wasnt doing any damage by using the amp.

[amptech]

Hi black labb,
popping sounds at switch in transistor amps, a helpful tip is to use a simple relay timer circuit placed between speaker o/p of your to the speaker set it to 5 seconds.
amptech.

[TD_Madden]

or just unplug the sp[eaker before turning it off....won't hurt nothin'